SELLAS Life Sciences Loses Arbitration Against 3D Medicines Over GPS Milestone Dispute

Arbitration Decision Dismisses SELLAS Claims Against 3D Medicines

On July 24, 2026, a sole arbitrator rendered a decision in the binding arbitration proceeding between SELLAS Life Sciences Group, Inc. and 3D Medicines, Inc., administered by the Hong Kong International Arbitration Centre. The arbitrator dismissed the Company's claims in their entirety. This decision concludes a dispute that SELLAS had previously commenced against 3D Medicines regarding certain matters related to their collaborative arrangement involving galinpepimut-S, a therapeutic candidate being developed for the Greater China territory.

The arbitration proceeding was administered under Hong Kong International Arbitration Centre rules, which permitted the arbitrator to administratively allocate costs related to the dispute. As a result of the decision, SELLAS has been ordered to bear a portion of 3D Medicines' legal fees and related expenses. The company disclosed that this allocated amount totals approximately $1.0 million. This cost allocation represents a financial consequence of the unsuccessful arbitration claim brought by SELLAS against its collaborative partner.

Disputed Milestone Payments and License Agreement Terms

At the heart of the arbitration dispute were certain milestone payment obligations tied to the development and commercialization of galinpepimut-S in the Greater China territory. The filing indicates that $13.0 million in milestone payments were specifically in dispute in the arbitration proceeding. These disputed payments were part of a larger portfolio of potential future milestone payments available under the exclusive license agreement between SELLAS and 3D Medicines.

As of March 31, 2026, the exclusive license agreement contained $191.5 million in potential future milestone payments. Following the arbitrator's decision, 3D Medicines announced its intention to continue progressing the development and commercialization of galinpepimut-S in accordance with the terms of the exclusive license agreement. This statement suggests that the underlying commercial arrangement between the two parties remains in effect and that the disputed milestone payments were not the foundation of the partnership's continuation.

Cash Position and Financial Status as of Mid-Year 2026

SELLAS disclosed its unaudited cash and cash equivalents position as of June 30, 2026, reporting an estimated $138.3 million. The company explicitly noted that this amount is preliminary and unaudited, remaining subject to completion of financial closing procedures and management reviews. As a result, the cash position disclosed may differ materially from the final amount reflected in the Company's audited financial statements for the six months ended June 30, 2026.

The disclosure of cash reserves at this level suggests SELLAS maintains a foundation for ongoing operations and research and development activities. However, investors should note the preliminary nature of this figure and await the completion of the company's formal financial closing procedures before drawing final conclusions about the company's liquidity position at mid-year 2026. The arbitration-related payment of approximately $1.0 million in legal fees would reduce this cash position once finalized.

Galinpepimut-S Development Strategy in Greater China

Galinpepimut-S, commonly referred to as GPS, is the therapeutic candidate at the center of the SELLAS and 3D Medicines partnership. The exclusive license agreement grants 3D Medicines the rights to develop and commercialize GPS in the Greater China territory, a significant market opportunity for oncology and immunotherapy candidates. The announcement that 3D Medicines intends to continue advancing GPS under the terms of the existing agreement underscores the perceived commercial potential of this asset in that geographic region.

The continuation of GPS development by 3D Medicines, despite the arbitration loss by SELLAS, indicates that the partnership structure itself was not jeopardized by the dispute. Rather, the arbitration centered on specific contractual interpretation or performance issues related to milestone achievement or payment obligations. The $191.5 million in remaining potential milestone payments as of March 31, 2026 represents the upside SELLAS retains if GPS achieves defined development and commercialization milestones in Greater China.

Regulatory and Compliance Context of the Arbitration Proceeding

The use of the Hong Kong International Arbitration Centre for resolving the dispute reflects the international nature of the SELLAS-3D Medicines partnership and the geographic focus of the license agreement on Greater China. Arbitration administered by HKIAC provides a neutral, international forum for resolving cross-border commercial disputes, and its rules governed the allocation of costs in this proceeding. The arbitrator's discretionary authority to allocate legal fees under HKIAC rules resulted in SELLAS bearing approximately $1.0 million of 3D Medicines' defense costs.

The binding nature of the arbitration decision means that SELLAS's remedies for contesting the outcome are limited. Arbitration decisions are generally final and enforceable under international arbitration conventions, providing both parties with certainty regarding the dispute's resolution. The dismissal of SELLAS's claims and the cost allocation are therefore binding determinations unless the company pursues limited grounds for challenge under applicable arbitration law.

Financial Impact and Reported Metrics

The immediate financial impact of the arbitration decision includes the $1.0 million allocation of 3D Medicines' legal fees and costs to SELLAS. This represents a direct reduction to the company's cash position and a quantifiable cost associated with the unsuccessful arbitration proceeding. Additionally, the loss of the disputed $13.0 million in milestone payments that were at issue removes a potential near-term cash inflow that SELLAS may have anticipated, though the specific timing and conditions for those payments were not disclosed in this announcement.

Beyond the direct financial impact, the arbitration decision may influence investor perception of SELLAS's contractual arrangements and dispute resolution outcomes. However, the filing does not disclose any other financial, operational, or strategic consequences related to the arbitration loss. The company's cash position of $138.3 million as of June 30, 2026, remains substantially above the $1.0 million cost allocation, suggesting adequate liquidity for near-term operations.

Strategic Implications for SELLAS and Asset Monetization

The arbitration outcome underscores the challenges SELLAS may face in realizing value from its out-licensed assets and collaborative partnerships. Galinpepimut-S represents a significant component of SELLAS's pipeline and value proposition, with development and commercialization rights held by 3D Medicines in Greater China. The loss of this arbitration dispute may impact SELLAS's leverage in future negotiations or disputes with 3D Medicines or other partners regarding milestone achievement or payment obligations.

Despite the arbitration loss, the continuation of GPS development by 3D Medicines and the availability of $191.5 million in remaining potential milestone payments provide SELLAS with ongoing opportunities to realize value from this asset. The company's ability to successfully monitor development progress and validate milestone achievement will be critical to capturing these future payments. Investors may be watching for updates on GPS development progress and any changes to the milestone payment timeline or achievement likelihood.

Emerging Growth Company Status and Disclosure Obligations

SELLAS indicated in the filing that it is not currently designated as an emerging growth company under the Securities Act of 1933 or the Securities Exchange Act of 1934. This designation status affects the company's financial reporting and disclosure obligations, with non-emerging growth companies subject to full compliance with all applicable accounting standards and disclosure requirements without extended transition periods. The company's compliance with standard disclosure obligations is reflected in the current announcement of the arbitration outcome and preliminary financial position.

The company's principal executive offices are located at 7 Times Square, Suite 2503, New York, NY 10036, with registered securities traded on The Nasdaq Stock Market under the ticker symbol SLS. SELLAS's Delaware incorporation and commission file number 001-33958 are consistent with its regulatory standing as a publicly traded biopharmaceutical company subject to Securities and Exchange Commission oversight and reporting requirements.